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 and l!ie strata arp FstLmalcl to end nt 4,000 f<!Ct in depth. Eren if they do est*ml ileeper, mining woulil be impracticaible becanse oS the expense; and, be- sides, the leiDperaturu wouUl he 110= F, Ttie deep- est coHl-pit in England Is 2,413 feet, but one In Bel- gium extends 3.490 feet

In 1831, 154.000,000 tons were extracted, — enough to builJ fifty-flve great pyramids, or rebuild the great nail of China and add one-quarter to its lengtli. The tota] amount of coal luiiicd since 1954, would build a column S feet 4 inclies [n diameter, a dlslance of 240,000 miles, i.e.. to the moon. The output shows considerable fluctuation from year tn year. — as might bo eipecied from the variety of accidental circumstances, such as new invenllons, the mean annual temperature, and the slale of trade, — but, on the whole, a very rapid increase; the output for 1875 being double of that for 1354, and that for I8S3 double of tlial for 1862; and, if the amount ex- tracted increases at this rate (3,000,000 tons annu- ally), the supply will tie exhausted in the year 2145 A,D. The exhaustion will be theoretical only; for in a comparatively short lime Ihe price of coal will increase, and the demand necessarily lessen, so that coal will never be exhausted. One of four things must then happen, — either some new source of en- ergy must be supplied, or a larger per cent of the coal must be utilked, or coal must be imported, or England must give up her manufactories. It la doubtful if any new source of energy on a large scale will be discovered, unless some explosive be used for the purpose. According to Sir William Thomson, energy in the form of electricity can be transferred three hundred miles through a copper rod, with a loss of only twenty per cent: so in this way water- falls may be utilized In the future.

While it is hardly .possible to use less coal, we may get more energy out of it; for at present, out of a theoretical 10,000,000 foot-pounds of work which one pound of coal can supply, we only get 1,000,000 foot- pounds, lint Instead of a decrease In the waste, there Is likely, on the contrary, to be an increase; for each year faster speed Is demanded by rail, and Bleamshlps are rapidly replacing sailing- vessels. It might be possible to prevent the annual exporta- tion of 22,880,000 tons by export duties; but that does not seem expedient. The idea of importation is hardly practicable, for the nearest coal-mines of any extent are in Canada and the United Slates. The former are not easy of access, but are almost unlimited ; and those in the United States contain at least tbirty-eight times as much coal as those In England. To supply England with the necessary coal, 2. 100 ships as large as the Faraday, each carry- ing S,000 ton9 and making thirteen trips a year, would be required. The cost would be necessarily greatly Increased. In former times, England produced Its own breadstufTs: now the greater part Is imported, If coal Ijecomes scarce, there will lie no way of pay- ing for food, emigration will begin, the death-rate will Increase, the birtb-rate decrease, and England will change once more to an open, cultivated country, devoid of all other industries.

��PaEHISTORlC AMERICA. This translation of Na<iaillac"s ' Prehistoric America.' wc are told, is ina<le with the au- thor's sanction ; and it is also by his permis- sion that certain portions of the work have been so ' modified and revised ' as to bring them " into harmony with the results of recent investigation, and the conclusions of the beat authorities on the archaeolc^y of the United States." Speaking in a general waj", these changes and additions may be said to be con- fined almost entirely to the chapters that re- late to North America, ami to consist, not iu the discovery of new troths. althoiigU some additional facts are offered, hut in Ihe adop- tion of certain theories, as jmBitive conclusions, which, in the original publication, are given as explanations, more or less probable, of the points at issue. Thus, for instance, in that portion of the work which refers to the origin and antiquity of man in America, we arc given to understaud that he is probably of Aaialie descent, all other theoriee being practically ignored. To this explanation, considered sim- ply as such, we do not object. AppearRnoes certainly favor it ; and as it is the most satis- factory waj- of accounting for his presence here, and for certain peculiar features in iiis civiliza- tion, we do not see any reason why it shonld not be accepted, at least until something bet- ter is offered. That his ancestors airived here at a i^riod so remote that it can only be meas- ured by geological epochs and phases of civili- zation, is conclusively proved ; and though it is not equally susceptible of demons trail on, yet we think it highly probable that these im- migrants may have started from different cen- tres, and gradually pushing their way westward across Bering Strait, and by way of the Poly- nesian Islands, may have landed at different times, and at different places, on the shores of both North and South America. That they belonged to different races, and were in differ- ent stages of development, is possible; and whilst we are willing to admit that "the cul- ture which can be traced from the sbell-henp to the mound, from the mound to the pueblo, and from the pueblo to the structures of Mexico, Central America, and Peru, is distinctively American," we may be pardoned for suggest- ing that it is possible, in view of what is said of the facilities of intercourse, not only between our tribes but between the continents, that this culture may have been colored by Asiatic influ- ences of a comparatively recent date.

PrrMnUrli: Amtrli:a. Uy tbe lilAaguis DB NjkD&II.i.At>. TmniUlffll by N. U-ADTe». Kdiled by W. H. D.ll, New York. (1. P. I'utnam-t Km, ISSI. M« p., lllmtr. f.

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